1. Field of the Invention
The present application relates generally to devices for delivering respiratory gas or gases in medical applications, and more particularly, to new and improved disposable respiratory face masks which are adapted for use on patients prior to, during or after surgery. Even more particularly, the present invention relates to a respiratory face mask and headstrap assembly that is especially useful in administering gases, such as anesthesia or oxygen, or mixtures of same, for medical purposes, and as such represents an improvement over the similar device or devices disclosed in my prior application.
2. Description of the Prior Art
In my prior application, there is fully disclosed a disposable anesthesia face mask assembly having a flexible hollow inflatable sealing cushion extending along substantially the entire peripheral edge of the mask shell or body member to prevent anesthesia gas or the like delivered through the gas portal on the mask from escaping and adversely affecting the surgical environment. As further disclosed in my prior application, by fitting such a sealable mask on the patient's face and anchoring the bottom portion thereof underneath the chin of the patient, the mask is rendered stable whereas displacement toward the ocular area or elsewhere is prevented under virtually all conditions likely to be encountered during the ensuing surgical procedure, and especially so during relatively long-duration procedures. As disclosed in my prior application, advantageous use of the face mask is facilitated by the employment of a relatively simple headband or strap (preferably elastic) adapted to engage at the strap's opposed free ends only the peripheral rim or edge of the mask body member via strap anchoring lugs projecting laterally and oppositely from the mask rim's edge. By this relatively simple arrangement, the mask may be held comfortably stable on the patient's face without employing excessive strap pressure. Thus, when the mask of my prior application is so used, anesthesia personnel do not have to be concerned about holding the mask in place on the patient's face thereby freeing both hands to attend to other important tasks.
Masks for delivering anesthesia gas, oxygen or the like to patients undergoing surgery are widely used in the administration of general anesthesia (GA), an anesthetic procedure where patients are unable to breathe on their own and this function must be assisted by a ventilator usually through an endo-tracheal tube (intubation) or a laryngeal mask airway (LMA). These prior art masks (used in GA) cover merely the nose and the mouth portions of the patient's face and usually are held in place by the hand or hands of attending anesthesia personnel. Attempts have been made to affix such prior masks to the patient's head and face, but in so doing relatively bulky and cumbersome strap assemblies must be used. These prior strap assemblies, in turn, require relatively excessive pressure to maintain mask stability because of the limited footprint of the mask's pneumatic sealing cushion. For example, U.S. Pat. No. 5,975,079 (Hellings et al) discloses an anesthesia face mask with a removable headstrap plate adapted to fit over the breathing circuit connecting portal extending centrally from the face mask. The plate has four hooks for attachment to a strap assembly which, in turn, features a central body and four attaching prongs connectable respectively to the hooks on the plate.
U.S. Pat. No. 6,981,503 (Shapiro) shows a mask similar to that disclosed in the '079 patent, but furthermore adds a pair of retaining straps 70 and 80 adapted to be placed underneath the patient's chin for attachment to the lower pair of headstrap extensions 64 and 66 (see FIGS. 6 and 7).
The unique face mask assembly disclosed in my prior application represents a significant advance over the foregoing body of prior art because, inter alia, it is the only respiratory or anesthesia mask now known having a pneumatic sealing cushion that extends over and under the chin portion of the patient's face and surprisingly, as a result of this unique arrangement, requires only a relatively simple single headstrap or band for maintaining the mask in a stable position even during long duration surgical procedures. Hence, the mask and headstrap assembly of my prior application is ideally suited for use during so-called “sedation” anesthesia procedures where the patient breathes on its own and which is characterized in the medical art as “Monitored Anesthesia Care” (MAC). The American Society of Anesthesiologists (ASA) defines MAC in part as “a specific anesthesia service in which an anesthesiologist has been requested to participate” and which includes “administration of sedatives, analgesics, hypnotics, anesthetic agents or other medications necessary to ensure patient safety and comfort.” As pointed out in my prior application, the face mask assembly disclosed therein may be used to administer anesthesia gas or gases, oxygen, and/or mixtures of same during MAC.
More specifically, with the mask assembly of my prior application, the headstrap opposed ends are adapted to be connected respectively to a pair of lugs projecting laterally from the rim of the mask shell or body. Such lugs may deflect in use causing one or both strap ends to detach and because the lugs are oriented substantially perpendicular to the tension forces in the headstrap, such deflection is more easily effected than desired. Additionally, the attachment headstrap lugs have a T-bar distal end which is relatively difficult to mold and presents the possibility of snagging foreign objects in the surgical environment.
In order to overcome the foregoing disadvantages, the present application discloses a new and improved headstrap and strap attachment system for the mask assembly disclosed in my prior application, or for similar devices.